1. Field of the Invention
This invention relates to a document handling apparatus for a copying machine, and, in particular, relates to a document handling apparatus having separate means for moving a thick or a thin original document across the illuminating station of the copying machine.
2. Description of the Prior Art
In the field of copy machines, especially machines designed for a low volume of usage, there are several kinds of devices for handling single sheet or thin-type documents as well as bulky or thick-type documents, such as books. One kind of device uses a fixed transparent platen on which both types of documents are positioned for copying. The document is either scan exposed by a moving optical system or flash exposed. Unfortunately, moving optical systems are complex and expensive and flash exposure systems are bulky and so they require more machine space than is desirable for a low volume copy machine. Other copy machines use a fixed optical system and scan expose a document by moving it across an illuminating station. For example, one machine uses a reciprocating carriage for handling both thick and thin documents in transit across a fixed illumination station. However, such a device is inherently slow since no copying can be done half the time that the carriage is in motion. Another machine permanently mounts feed rollers on opposite sides of a fixed illuminating station for handling single sheet, thin documents which are rapidly fed across the illuminating station by the feed rollers. But, with such a device, thick documents cannot be copied at all.
Accordingly, it has been proposed to combine a reciprocating carriage and feed rollers into a single document handling apparatus in such a way that the feed rollers do not interfere with the transit of the carriage and thereby obtain the benefits of both kinds of document handlers. One such combination is shown in U.S. Pat. No. 3,728,015 where in one embodiment a set of upper feed rollers are fixedly mounted to the carriage and a set of lower rollers are mounted on the machine. In another embodiment of that device, both sets of rollers are fixedly mounted to the carriage. Other devices having thin original feed rollers mounted on a reciprocating carriage are also shown in U.S. Pat. Nos. 3,790,272 and 3,740,133. Still another device that has feed rollers detachably mounted to a carriage is shown in U.S. Pat. No. 3,806,239. Hence, when copying thick originals with one of the above devices, the thin document feed rollers are either removed by an operator or moved with the carriage.